for a vector, every four data get an average ,then put them into a new vector , its length will be the old's one fourth,how to make it quickly

sometimes it may get average every 5 nums, it will be better to create a function

[Cedric]

What have you done so far?

Answer 1

[Star Strider]

This works:

Data = randn(1,25);                     % Create Data (# Columns = multiple of 4)
N = 4;                                  % Number to take the means over
Data = Data(1:N*fix(size(Data,2)/N));   % Truncate Data vector if necessary
DataRs = reshape(Data, N, []);          % Create NxM matrix
DataRsMean = mean(DataRs,1);            % Take column means to create desired result

To get average over 5, change the N = 4 to N = 5.

[Roger]

nice, thanks

[Star Strider]

My pleasure!